Weegy: Rule 1) The Derivative of any constant is always zero. You can know constants because they do not change with any variable. [ So if C never changes no matter what x (or any other variable) does, for example, then C is a constant and dC = C'(x) = 0 dx Examples: The number, 14, doesn't change no matter what else varies. So the derivative of 14 is zero. The value of p doesn't change no matter what else changes, so the derivative of p is always zero. If a circle of fixed size has radius, r, then r is constant and the derivative of r is zero. ] User: how much is x? User: x*(x-1)=42, how much is x? Weegy: 2x-1x = 42 x=42 (More)